NetGear's ReadyNAS 2100 has 4 disk slots and costs $2000 with no disks. That seems a bit too expensive for just 4 disk slots.
Dell has good network storage solutions too. PowerVault NX3000 has 6 disk slots, so that's an improvement. However, it costs $3500; the NX3100 doubles the number of disks at double the price. Just in case I'm looking at the wrong hardware for lots of storage, the trusty PowerVault MD3000i SAN has a good 15 drives, but it starts at $7000.
While you can argue about support from Dell, Netgear or HP or any other company being serious, it's still pretty damn expensive to get those drives RAID'ed together in a box and served via iSCSI. There's a much cheaper option: build it yourself. Backblaze has built it's own box, housing 45 (that's forty five) SATA drives for a little under $8000, including the drives themselves. That's at least 10 times cheaper than current offers from Dell, Sun, HP, etc.
Why is NAS (or SAN – still storage attached to a network) so expensive? After all, it's main function is to house a number of HDDs, create a RAID array and serve them over a protocol like iSCSI; nearly everything else is just colored bubbles (AKA marketing terms).
Best Answer
This really depends on your point of view.
If I'm an ISV who needs to launch on the tiniest possible budget but I need a crapload of storage, then yes, a brand-name box will be too expensive and the risk/reward of a home-made FreeNAS box would most likely be an acceptable solution.
However, if I'm a mega-multi-national corporation with 10,000 users and I run a datacentre that supports a billion-dollar-a-year company and if the datacentre goes offline it's going to cost in the order of $100,000 a minute then you can bet your arse I'm going to buy a top-shelf brand-name NAS with a 2-hour no-questions-asked replacement SLA. Yes, it's going to cost me 100x more than a DIY box, but the day your entire array fails and you've got 10TB of critical storage offline, that $100,000 investment is going to pay for itself in about 2 hours flat.
For someone like Backblaze, where storage volume is king, then it makes sense for them to roll their own - but that's the core competancy - providing storage. Dell, EMC, etc - their products are aimed at those who storage is not their primary focus.
Of course, it's all totally pointless if you don't have backups, but that's another story for another day.